PROJECT SUMMARY Stress urinary incontinence (SUI) is defined as involuntary loss of urine secondary to an increase in abdominal pressure during events such as sneezing, coughing or laughing in the absence of bladder contractions. This disorder is a significant gynecological/urological problem currently affecting approximately 25 million American women. These SUI patients exhibit the high incidence of intrinsic sphincter deficiency, characterized by a malfunction of the urethral sphincter mechanism resulting in the low-pressure urethra. The etiology of SUI may include childbirth-associated injuries to muscles, connective tissues and nerves as well as aging and menopause (estrogen deficiency). However, there is little information as to pathology- specific mechanisms inducing changes in urethral closure function. Therefore, in this application, we will fully elucidate how the proposed risk factors for SUI such as estrogen deficiency, aging process and birth trauma contribute to the progression of the SUI condition, and to provide a proof of concept for novel gene therapy approaches for the treatment of SUI using herpes simplex virus (HSV) vector-mediated gene delivery of growth factors such as insulin-like growth factor-1 (IGF-1) and glial-cell derived neurotrophic factor (GDNF) in animal models of SUI. The Specific Aims of this proposal are: (1) to evaluate functional and molecular changes of the urethral function leading to SUI using rat models of SUI induced by multiple simulated birth trauma (3 times vaginal distension, VD), estrogen deficiency (ovariectomy, OVX) and aging (14 months old), (2) to investigate the effect of IGF-1 gene therapy using replication-defective HSV vectors in 3 different SUI animal models, and (3) to investigate the effect of glial-cell derived neurotrophic factor GDNF gene therapy using replication- defective HSV vectors in 3 different SUI animal models. We anticipate that IGF-1 gene therapy is more suitable for the recovery of urethral tissue damage (striated & smooth muscle and extracellular matrix molecules) whereas GDNF gene therapy could be more effective for the nerve damage (somatic and autonomic) to exert the therapeutic effects on SUI. By defining the detailed urethral pathology of SUI and the feasibility of HSV vector-mediated gene therapy approaches, we can provide the foundation for new therapies of SUI and offer the hope of prevention and reversal of this potentially devastating condition to greatly improve the women's health. This is recognized as a high priority in the urologic/gynecologic care of SUI women. 1